| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |
Arguments: pixmap
Returns (or sets with setf)
whether the rows of pixels in pixmap are ordered such that they would
appear inverted in the printed representation of the pixmap
contents. That is, if invert-p is true, it indicates that the first
row in the pixmap contents is the bottom row of pixels in the actual
image, though that row will appear on top when the pixmap contents are
printed. invert-p does not
normally need to be set by an application, since Common Graphics
internally knows how to handle either mode. The default is nil
, so that when the contents of a pixmap are
specified as a static list of lists in lisp source code, the source
ccode will be oriented the way that the actual image would appear in a
window.
Note that the Windows operating system expects the first row of pixels
to be the bottom of the image, and so what Common Graphics refers to
as an "inverted" pixmap is actually the most natural orientation for
the OS. When invert-p is
nil
, Common Graphics internally tells the OS
to flip the pixmap whenever it is drawn, and so it may be that a
pixmap that does not use a pixmap-handle draws somewhat faster when invert-p is true. And more important,
there is a bug that is apparently in Windows 95 (but not later
versions of Windows) where sometimes a pixmap will not appear at all
when copied to a window if the pixmap's invert-p property is nil
and it does not use a pixmap handle. There is no
workaround for this Windows 95 bug other than providing a handle with
open-pixmap-handle or defining the
pixel array so that the bottom row of pixels is the first row of the
contents list (setting the invert-p property of the pixmap to
true).
invert-p is a
property of the pixmap
class.
Copyright (c) 1998-2016, Franz Inc. Oakland, CA., USA. All rights reserved.
This page was not revised from the 8.1 page.
Created 2010.1.21.
| Allegro CL version 8.2 Unrevised from 8.1 to 8.2. 8.1 version |